[Linux-cluster] GFS on 2.6.8.1

From: Daniel McNeil <daniel osdl org>

To: linux-cluster <linux-cluster redhat com>

Subject: [Linux-cluster] GFS on 2.6.8.1

Date: Fri, 01 Oct 2004 16:12:23 -0700

Hey all,
I finally got my 3-node fibre channel cluster up and running
on 2.6.8.1 and the latest GFS bits.
My setup:
3 machines each:
2 processor (800 MHZ Pentium 3)
512MB of memory
2 100Mb ethernet (1 public, 1 private)
1 2-port Qlogic FC host adapter
2 F/C sitches cascaded together
1 - 10 disk - dual controller FASTT200 (36GB 10,000rpm drives)
I am just starting to test and did a quick untar test to
see approximate performance of gfs compared to ext3.
I only have gfs mounted on 1 node for this test.
Here are the results:
The command run was 'time tar xf /Views/linux-2.6.8.1.tar'
where /Views is an NFS mounted file system and the current
working directory is in a clean file system on a single
disk drive.
real user sys
ext3 data=ordered 0m16.962s 0m0.552s 0m6.529s
ext3 data=journal 0m39.599s 0m0.501s 0m5.856s
gfs 1-node mounted 1m23.849s 0m0.890s 0m17.991s
The 2nd test was removing the files (time rm -rf linux-2.6.8.1/)
real user sys
ext3 data=ordered 0m1.225s 0m0.021s 0m1.048s
ext3 data=journal 0m1.286s 0m0.024s 0m1.038s
gfs 1-node mounted 0m49.565s 0m0.094s 0m8.191s
Questions:
1. Is GFS doing the equivalent of data=journal?
If it is, it is twice as slow as ext3 data=journal.
Is this expected?
2. What is going on in the remove that is taking so long?
With only 1 node mounting a gfs file system (3 node cluster)
I should master all the locks.
3. If I re-ran the tar test after the remove (without umount/mount),
the tar times were basically the same. I would have expected
GFS to cache the free inodes and have a faster 2nd tar time.
When does GFS stop caching the inode (and the dlm locks on the
inodes?)
Now, on to more testing!
Thanks,
Daniel